Integrin αvβ3 receptor antagonists have been described as being of use for the prevention and/or treatment of osteoporosis, vascular restenosis, macular degeneration, diabetic retinopathy, atherosclerosis, inflammatory arthritis, cancer, and metastatic tumor growth see, for example, M. E. Duggan, et al., “Ligands to the integrin receptor αvβ3, Exp. Opin. Ther. Patents, 10: 1367–1383 (2000); M. Gowen, et al., “Emerging therapies for osteoporosis,” Emerging Drugs, 5: 1–43 (2000); J. S. Kerr, et al., “Small molecule αv integrin antagonists: novel anticancer agents,” Exp. Opin. Invest. Drugs, 9: 1271–1291 (2000); and W. H. Miller, et al., “Identification and in vivo efficacy of small-molecule antagonists of integrin αvβ3 (the vitronectin receptor),” Drug Discovery Today, 5: 397–408 (2000)].
U.S. Pat. No. 6,017,926, assigned to Merck & Co., describes a class of 2-oxo-imidazolidin-1-yl-propionic acid derivatives, which are potent integrin αvβ3 receptor antagonists and therefore useful for inhibiting bone resorption, vascular restenosis, treating and/or preventing osteoporosis, and inhibiting diseases and conditions associated with excessive and undesirable angiogenesis. Specifically disclosed in U.S. Pat. No. 6,017,926 is 3-{2-oxo-3-[3-(5,6,7,8-tetrahydro[1,8]naphthyridin-2-yl)propyl]imidazolidin-1-yl}-3-(6-methoxy-pyridin-3-yl)propionic acid. Pharmaceutically acceptable salts of this compound are generically encompassed within the scope of U.S. Pat. No. 6,017,926.
However, there is no specific disclosure in the above reference of the newly discovered amine salts of 3-{2-oxo-3-[3-(5,6,7,8-tetrahydro[1,8]naphthyridin-2-yl)propyl]imidazolidin-1-yl}-3-(6-methoxy-pyridin-3-yl)propionic acid of structural formula I below of the present invention.